Well, the way I explained it is simplified. At all times, there is some degree of most of protein's pathways going on. I'll try to work under your assumptions. So you're saying 200g of protein will be the max that is utilized to help maintain the body's protein stores, repair damaged muscle tissue, etc. If you ate 400g, the extra 200g would go into other processes. As I said, the process known as gluconeogenesis actually allows select amino acids to be converted into glucose. Glucose will then be used to help run the body via oxidative pathways at rest (aerobic glycolysis, the citric acid cycle). The body may, to a certain degree, then continue using that glucose to convert to fat directly after a meal (because it does immediately store excess food as glycogen, fat for utilization later in the day). Like I say though that will be used before the day is done so overall you will not have gained fat.
The big thing about eating excess protein is that it's unnecessary and doesn't necessarily provide a lot of nutrition. Think about a chicken breast. It's high in protein. What else? May a little bit of cholesterol your body can utilize to synthesis steroid hormones. Great. But if you think about it, there aren't antioxidants. There aren't really any vitamins. There aren't many minerals.
Research has shown that even high level power athletes don't experience extra gains in terms of hypertrophy, body composition, etc above 2g of protein intake per kg body weight. That's essentially eating 1g per pound of body weight of protein. So really if you're eating more than that, I'd say you're doing yourself an injustice by not eating more foods that could do more for your body.
Also, some people say excess protein is hard on your kidneys which is a farce. She may be operating under that belief, but it only applies in people who have kidney pathology. In that case, excess protein can excessively stress the kidney resulting in exacerbated kidney failure and more.
Things to consider: if you're not eating lean meats, then the excess fat may not be ideal for your artery or heart health. I say this under the stipulation that you eat "too much" meat. And I assume "meat" means fatty meat as well.